Josh...about those FETs

[RangerMan Premium Member]

I checked them all and they are all fine, foward and reverse. What I originally thought it was was the Cross Polarity Diode, but it too checks out. I cannot think of anything else that could possibly be wrong. Do you have any suggestions? What the amp is doing is cutting on, and shorting itself out to shut down.

Thanks man,

RM

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[jlaine 10+ year member]

Originally posted by RangerMan I checked them all and they are all fine, foward and reverse. What I originally thought it was was the Cross Polarity Diode, but it too checks out. I cannot think of anything else that could possibly be wrong. Do you have any suggestions? What the amp is doing is cutting on, and shorting itself out to shut down.

Thanks man,

RM

RM, diagnosis from here is very difficult, but are you sure the amplifier itself is shorting out?

Have you checked the voltage rails on the power supply itself to see if it is functioning properly? Without a working unit or the electrical schematic, it'll be hard to guess what they float at, but see if you can find a voltage present or not. What makes you think it is a direct short?

 

[RangerMan Premium Member]

Originally posted by jlaine RM, diagnosis from here is very difficult, but are you sure the amplifier itself is shorting out?

 

Have you checked the voltage rails on the power supply itself to see if it is functioning properly? Without a working unit or the electrical schematic, it'll be hard to guess what they float at, but see if you can find a voltage present or not. What makes you think it is a direct short?

I believe it is a direct short, b/c as soon as I cut the amp on, the inline fuse pops. I searched and searched for a schematic on this particular amp, and even e-mailed JBL for one, but nothing was sent. The power supply (battery?) is working well, because it is powering my new amp. If you know where to get a schemie, let me know.

I really appreciate it!

RM

 

[jlaine 10+ year member]

Originally posted by RangerMan I believe it is a direct short, b/c as soon as I cut the amp on, the inline fuse pops. I searched and searched for a schematic on this particular amp, and even e-mailed JBL for one, but nothing was sent. The power supply (battery?) is working well, because it is powering my new amp. If you know where to get a schemie, let me know.

 

I really appreciate it!

RM

I know of nobody inside JBL, so me getting the schematic is not plausible at this point.

The power supply I am speaking of is the power supply inside the amplifier RM, it may not be the output fets that are damaged, it may be the PS that has the damage.

 

[RangerMan Premium Member]

Originally posted by jlaine I know of nobody inside JBL, so me getting the schematic is not plausible at this point.

 

The power supply I am speaking of is the power supply inside the amplifier RM, it may not be the output fets that are damaged, it may be the PS that has the damage.

Alright, I'll check that tommorrow. I really appreciate your help, b/c I am an idiot when it comes to amps